The long-term goal of the proposed work is to understand the role of cell adhesion in the development and maintenance of healthy ocular tissues. Using the chick embryo as a model system, considerable progress has been made during the prior project period in the analysis of mechanisms which regulate the expression and function of cell adhesion molecules during neural retina and retinal pigment epithelium development. Progress towards the long-term objectives of the project will continue with experiments designed to address the following objectives. Specific aim 1. To determine which cadherin adhesion molecules are expressed during development of the neural retina (NR) and retinal pigment epithelium (RPE) and to determine the timing and pattern of their expression. Specific aim 2. To determine the mechanisms of regulation of expression and function of cadherins during development of the neural retina and retinal pigment epithelium. Specific aim 3. To determine the functional roles of cadherins during NR and RPE development and pathology. These studies will focus on elucidating the patterns of expression and mechanism which regulate the expression of cadherin cell adhesion protein molecules in the developing eye. The studies are of importance for understanding regulation of cell interactions in the eye, because malfunctions of these interactions are likely to contribute to ocular diseases such as retinal degeneration, proliferative vitreoretinopathy, and retinoblastoma.